1. Field of the Invention
The field of the invention relates to processing of digital data streams with error management. More particularly, the invention relates to processing of digital data streams with error management in wireless systems.
2. Description of the Related Art
Widespread use of the Internet and wireless communication has increased demand for multimedia services that stream media over the Internet and mobile/wireless channels. In Internet Protocol (IP) networks, multimedia can be provided by a server and can be streamed to one or more wired or wireless clients. Wired connections include dial-up, integrated services digital network (ISDN), cable, digital subscriber line protocols (collectively referred to as xDSL), fiber, local area networks (LAN), wide area networks (WAN) and others. Electronic devices utilizing wireless communications include telephones (e.g., cell phones), personal data assistants (PDAs), hand-held and portable computers and others. In most, if not all of these applications, bandwidth requirements and/or restrictions necessitate that video processing utilize a source encoder incorporating various compression algorithms to analyze, quantify and represent multimedia data to convey the maximum information by expending a “minimum” number of bits.
Both wired and wireless communication links may be prone to errors. A part of transmitted data is “erroneous” when this part of data is lost or corrupted. Any erroneous part of this data lost or corrupted during transmission may impact decoding of the data at the decoder.
Depending on the nature of the channel errors (e.g., bit errors and/or packet loss) and the type of packetization, all or part of the data pertaining to one or more data packets could become erroneous during transmission due to error propagation. Error propagation can be made worse by compression schemes such as CAVLC, spatial prediction, and temporal prediction (e.g., motion compensated prediction) that depend on successful decoding of other portions of data.
Various methods of detecting erroneous packets have been employed including encoding checksums such as cyclic redundancy checks based on a portion of data contained in packet headers and/or the body of the packets. Erroneous packets are then detected and discarded. Some communication networks may support retransmission of discarded packets. However, some communication networks do not support retransmission and the information in discarded packets may be lost, thereby requiring resynchronization of the data stream. Discarding the erroneous packets may result in the data stream being undecodable due to loss of synchronization. Resynchronization points restrict the use of compression schemes such as, for example, CAVLC, spatial prediction, and/or temporal prediction that depend on previously received and decoded data. Thus, providing resynchronization points cuts down on the compression efficiency of the communication link.
Thus, there is a need for an improved method for managing erroneous packets rather than discarding erroneous packets and using resynchronization points in the data stream.